<<

Inorg. Chem. 2002, 41, 492−500

Chalcogen-Rich Lanthanide Clusters: Compounds with Te2-, (TeTe)2-, 5- 9- TePh, TeTePh, (TeTeTe(Ph)TeTe) , and [(TeTe)4TePh] ; Single Source Precursors to Solid-State Lanthanide Tellurides

Deborah Freedman, Thomas J. Emge, and John G. Brennan*

Department of Chemistry, Rutgers, the State UniVersity of New Jersey, 610 Taylor Road, Piscataway, New Jersey 08854-8087

Received September 19, 2001

Lanthanide react with PhTeTePh and elemental Te in pyridine to give (py)yLn4(Te)(TeTe)2(TeTeTe(Ph)- TeTe)(TexTePh) (Ln ) Sm (y ) 9; x ) 0); Tb, Ho (y ) 8, x ) 0.1)), and (py)7Tm4(Te)[(TeTe)4TePh](Te0.6TePh) clusters. The Sm, Tb, and Ho compounds contain a square array of Ln(III) all connected to a central Te2- . Two adjacent edges of the square are bridged by ditelluride ligands, with the Ln that is η2 bound to both of these TeTe ligands also coordinating to a terminal TePh ligand. The other two edges of the square are spanned by ditellurides that both coordinate a TePh ligand that has been displaced from the Ln ion by pyridine, to give the 2 2 5- pentaanion (µ-η -η -Te2Te(Ph)Te2). In the Tm compound, the displaced TePh interacts with all four TeTe units. The compounds are air-, light-, and temperature-sensitive. Upon thermolysis, they decompose to give solid-state

TbTe2-x, HoTe, or TmTe, with elimination of Te and TePh2.

Introduction energy surfaces, and the combination of ionic Ln and covalent Te ligands yields compounds that are particularly Inorganic compounds of are challenging syn- difficult to isolate and characterize. This is reflected in the thetic targets, because bonds to this element are considerably literature, where over a hundred examples of structurally weaker than bonds to the lighter sulfur or se- characterized compounds containing Ln-S bonds, more than lenium, and thus, compounds are relatively unstable. Because 35 examples of compounds with Ln-Se bonds, and only 12 this relative instability often to the formation of ma- analogous Ln-Te compounds have been described.3 A terials with highly unusual or useful physical properties (i.e., - 1 2 majority of the 12 Ln Te compounds contain relatively CdHgTe semiconductors, Bi Te thermoelectric materials ), - 2 3 electronegative, sterically demanding ancillary ligands4 7 the chemistry of metal tellurium compounds continues to (i.e., C Me or Cp*) that kinetically passivate the Ln-Te attract attention. From a fundamental perspective, compounds 5 5 bond. Most of the remaining examples are divalent Ln(ER) with Te are interesting because they often adopt unconven- 2 coordination complexes of the active Sm, Eu, or tional molecular or solid-state structures with a wide range - Yb.8 10 The tendency of the trivalent redox active metals to of Te-Te bonds, a chemistry that parallels that of the com- reductively eliminate RTeTeR clearly reflects the inability plex polyiodide compounds. Stabilities are defined by shal- of Te ligands to stabilize Ln(III) oxidation states. In the low potential energy surfaces, and structures are often un- absence of stabilizing ancillary anions, the only reported predictable. example of an isolable Ln(III)-Te compound is (Me2PCH2- Lanthanide (Ln) ions, with their 4f obitals ef- fectively shielded by filled 5s2 and 5p6 orbitals, also tend to (3) Nief, F. Coord. Chem. ReV. 1998, 178, 13. adopt molecular structures defined by shallow potential (4) Berg, D.; Andersen, R. A.; Zalkin, A. Organometallics, 1988, 7, 1858. (5) Evans, W. J.; Rabe, G. W.; Ziller, J. W.; Doedens, R. J. Inorg. Chem. 1994, 33, 2719. * Author to whom correspondence should be addressed. E-mail: bren@ (6) Zalkin, A.; Berg, D. Acta Crystallogr. 1988, C44, 1488. rutchem.rutgers.edu. (7) Recknagel, A.; Noltemeyer, M.; Stalke, D.; Pieper, U.; Schmidt, H. (1) Andresen, B. F.; Scholl, M. S., Eds. Technology and G.; Edelmann, F. T. J. Organomet. Chem. 1991, 411, 347. Applications XXIV; SPIE Proceedings Vol. 3436, San Diego, CA, (8) Khasnis, D. V.; Lee, J.; Brewer, M.; Emge, T. J.; Brennan, J. G. J. 1998. Am. Chem. Soc. 1994, 116, 7129. (2) Mathiprakasam, B.; Heenan, P., Eds., Proceedings of the Thirteenth (9) Brewer, M.; Khasnis, D.; Buretea, M.; Berardini, M.; Emge, T. J.; International Conference on Thermoelectrics; AIP Conference Pro- Brennan, J. G. Inorg. Chem. 1994, 33, 2743. ceedings 316, Midwest Research Institute, 1995. (10) Cary, D. R.; Arnold, J. Inorg. Chem. 1994, 33, 1791. 492 , Vol. 41, No. 3, 2002 10.1021/ic010981w CCC: $22.00 © 2002 American Chemical Society Published on Web 01/11/2002 -Rich Lanthanide Clusters

11,12 R CH2PMe2)2La(TeSi(SiMe3)3)3. Without this chelating tometer with Cu K radiation. GCMS data were collected on a phosphine ligand, the analogous Ce derivative, “Ce(TeSi- 5890 Series II gas chromatograph with an HP 5971 mass selective detector. (SiMe3)3”, decomposes below room temperature to give the 11,12 equally unstable tellurido cluster Ce5Te3(TeSi(SiMe3)3)9. Synthesis of (py)9Sm4(µ4-Te)(µ2-TeTe)2(µ2-TeTeTe(Ph)TeTe)- · While the past three years has experienced a burst of (TePh) 5py (1). metal (0.30 g, 2.0 mmol) and Hg (0.05 activity describing the synthesis and characterization of stable g, 0.25 mmol) were added to a solution of diphenyl ditelluride (0.82 g, 2.0 mmol) in pyridine (50 mL). The reaction flask was wrapped lanthanide clusters coordinated to chalcogenido (E2-,E) 13-18 in aluminum foil up to the stopper. The next day elemental tellurium S, Se) ligands, extension of this work to compounds of was added (0.38 g, 3.0 mmol) to the yellow solution and unreacted Te has not yet appeared. The recent high-yield synthesis of Sm. The following day the solution was dark red, and a brick red 2- 19,20 chalcogen-rich Ln compounds with (EE) ligands, rather solid had precipitated. The solution was filtered and layered with - than E2 ligands, from the reactions of lanthanide chalco- 20 mL of hexanes to give dark red needles (100 mgs, 10%) that genolates with elemental E, leads to the suggestion that could be separated by hand from the dark solid major product. 2- 2- (EE) may stabilize Ln ions more effectively than E , pos- Synthesis of (py)8Tb4(µ4-Te)(µ2-TeTe)2(µ2-TeTeTe(Ph)TeTe)- sibly to the extent that compounds with Te can be isolated (Te0.1TePh)·4.5py (2). metal (0.32 g, 2.0 mmol) and Hg routinely. This paper outlines initial investigations into the (0.05 g, 0.25 mmol) were added to a solution of diphenyl ditelluride synthesis, characterization, stability, and thermolysis of Te- (0.82 g, 2.0 mmol) in pyridine (50 mL). The flask was wrapped in rich Ln clusters. aluminum foil. After stirring for 1 day, elemental tellurium (0.38 g, 3.0 mmol) was added to the dark golden brown mixture that Experimental Section still contained unreacted Tb. Two days later the metal had been consumed and there was a significant amount of dark red precipitate. General Methods. All syntheses were carried out under ultrapure The flask was heated to between 60 and 75 °Cforca.1htodissolve nitrogen (JWS), using conventional drybox or Schlenk techniques. the red solid. The red solution was filtered into a flask with either Solvents (Fisher) were refluxed continuously over molten alkali a flat bottom (modified Erlenmeyer) or a large round-bottom and metals or K/benzophenone and collected immediately prior to use. concentrated by ca. 3 mL. Hexanes (ca. 8 mL) were added rapidly Anhydrous pyridine (Aldrich) was purchased and refluxed over into the solution that was then re-covered with aluminum foil and KOH. PhTeTePh was prepared according to literature procedures.21 allowed to stand at rt for 2 days to give deep red crystals (0.34 g, Ln and Hg were purchased from Strem. Melting points were taken 35%) that were washed with hexane (5 mL) and did not decompose in sealed capillaries and are uncorrected. IR spectra were recorded or melt below 300 °C. Anal. Calcd for C64.5H62.5N10.5Tb4Te11.1:C, - on a Mattus Cygnus 100 FTIR spectrometer from 4000 to 600 cm 1 25.5; H, 2.07; N, 4.84. Found: C, 25.3; H, 2.19; N, 4.33. IR: 3077 as Nujol mulls on NaCl plates. Electronic spectra were recorded (m), 2933 (s), 2856 (s), 1630 (w), 1597 (s), 1580 (s), 1481 (m), on a Varian DMS 100S spectrometer with the samples in a 0.10 1465 (s), 1437 (s), 1384 (s), 1218 (m), 1145 (w), 1068 (m), 1038 mm quartz cell attached to a Teflon stopcock. Elemental analyses (m), 1030 (m), 1004 (m), 991 (m), 825 (w), 745 (s), 732 (w), 702 were performed by Quantitative Technologies, Inc. (Whitehouse (s), 623 (w), 602 (m), 451 (w), 405 (w) cm-1. Magnetic susceptibil- NJ). These compounds are sensitive to the thermal dissociation of ity: µeff (5-250 K) ) 7.87 (500 G); 7.91 (10 kG). The compound neutral donor ligands at room temperature, so the experimentally does not show an absorption maximum from 350 to 800 nm in determined elemental analyses are often found to be lower than THF. No 1H NMR resonances were detected in either THF or the computed analyses. The reported values were closest to the pyridine. Thermolysis: 100 mg of 1 was placed in a quartz tube calculated values, but analytical determinations gave a range of under vacuum for 5 min. The tube was then sealed and the sample values that were usually consistent with the one of the three unit temperature was increased at the rate of 20 °C/min with one end cell formulations described below. was of the tube submerged in liquid nitrogen. The temperature was held measured on a SQUID magnetometer ina1Tfield. NMR spectra at 550 °C for 5 h and then the tube was removed and allowed to were obtained on either Varian 300 or 400 MHz NMR spectrom- cool rapidly to give ca. 25 mg of nonvolatile solid. Powder 22 eters, and chemical shifts are reported in δ (ppm). XR powder diffraction X-ray analysis revealed only TbTe2-x (0 < x < 0.3). diffraction profiles were obtained on a SCINTAG PAD V diffrac- Synthesis of (py)8Ho4(µ4-Te)(µ2-TeTe)2(µ2-TeTeTe(Ph)TeTe)- (Te0.1TePh)·4.5py (3): Method 1. metal (0.33 g, 2.0 (11) Cary, D. R.; Ball, G. E.; Arnold, J. J. Am. Chem. Soc. 1995, 117, mmol), Hg (0.05 g, 0.25 mmol), and diphenyl ditelluride (0.79 g, 3492. (12) Cary, D. R.; Arnold, J. J. Am. Chem. Soc. 1993, 115, 2520. 1.93 mmol) were added to pyridine (50 mL), the reaction flask (13) Freedman, D.; Emge, T. J.; Brennan, J. G. J. Am. Chem. Soc. 1997, was wrapped in aluminum foil, and the mixture stirred. The next 119, 11112. day elemental tellurium (0.38 g, 3.0 mmol) was added to the yellow (14) Melman, J. H.; Emge, T. J.; Brennan, J. G. Chem. Commun. 1997, 2269. solution and unreacted Ho. The following day the solution was dark (15) Freedman, D.; Melman, J. H.; Emge, T. J.; Brennan, J. G. Inorg. Chem. red, and a brick red solid had precipitated. The solution was filtered 1998, 37, 4162. into a Schlenk flask with an outer diameter of 41 mm, concentrated (16) Melman, J. H.; Emge, T. J.; Brennan, J. G. Inorg. Chem. 1999, 38, to 45 mL, layered with hexanes (20 mL), and then placed in the 2117. (17) Freedman, D.; Emge, T. J.; Brennan, J. G. Inorg. Chem. 1999, 38, dark to give dark red needles (100 mgs, 10%) that did not melt up 4400. to 310 °C but slowly turned black and began eliminating a gas at (18) Freedman, D.; Sayan, S.; Emge, T. J.; Croft, M.; Brennan, J. G. J. ca. 230 °C. Anal. Calcd for C H N Ho Te : C, 25.4; H, Am. Chem. Soc. 1999, 121, 11713. 64.5 62.5 10.5 4 11 (19) Melman, J. H.; Fitzgerald, M.; Freedman, D.; Emge, T. J.; Brennan, 2.07; N, 4.83. Found: C, 24.8; H, 2.06; N, 4.73. IR: 2865 (s), J. G. J. Am. Chem. Soc. 1999, 121, 10247. 2361 (w), 1596 (m), 1579 (s), 1463 (s), 1377 (s), 1216 (m), 1144 (20) (a) Kornienko, A.; Emge, T.; Brennan, J. G. J. Am. Chem. Soc. 2001, (m), 1067 (m), 1030 (m), 990 (m), 744 (m), 727 (m), 701 (s), 622 123, 11933. (b) Kornienko, A.; Melman, J. H.; Hall, G.; Emge, T. J.; Brennan, J. G. Inorg. Chem. 2002, 41, 121. (21) (a) Petragnani, N.; DeMoura, M. Chem. Ber. 1963, 96, 249. (b) Haller, (22) Pardo, M. P.; Flahaut, J.; Domange, L. Bull. Chem. Soc. Fr. 1963, W. S.; Irgolic, K. J. J. Organomet. Chem. 1973, 38, 97. 256, 953.

Inorganic Chemistry, Vol. 41, No. 3, 2002 493 Freedman et al. Table 1. Summary of Crystallographic Details for 1, 2, and 4a compound 12 4

empirical formula C82H80N14Sm4Te11 C64.50H62.50N10.50Tb4Te11.12 C57H55N9Te11.62Tm4 fw 3266.60 3039.98 3025.17 space (No.) P21/n (14) P21/c (14) C2 (5) a (Å) 12.191(5) 12.85(1) 23.407(7) b (Å) 27.484(5) 31.13(1) 23.20(2) c (Å) 28.484(5) 20.37(1) 17.507(9) R (deg) 90.00 90.00(5) 90.00 â (deg) 91.56(2) 91.50(5) 113.38(4) γ (deg) 90.00 90.00(5) 90.00 V (Å3) 9540(5) 8146(8) 8728(9) Z44 4 D(calcd) (g/cm-3) 2.274 2.479 2.302 temperature (°C) -120 -120 -120 λ (Å) 0.71073 0.71073 0.71073 abs coeff (mm-1) 5.770 7.378 7.869 R(F)b [I > 2σ(I)] 0.066 0.067 0.091 2 b Rw(F ) [I > 2σ(I)] 0.152 0.155 0.221

a b 2 2 2 2 2 2 1/2 Additional crystallographic details are given in the Supporting Information. R(F) ) ∑||Fo| - |Fc||/∑|Fo|; Rw(F ) ) {∑[w(Fo - Fc ) ]/∑[w(Fo ) ]} .

-1 (w) cm . Magnetic susceptibility: µeff (5-250 K) ) 10.6 (500 (w), 1632 (w), 1596 (m), 1579 (m), 1437 (s), 1366 (s), 1216 (m), G); 10.4 (10 kG). Unit cell (Mo KR, -120 °C): monoclinic space 1145 (m), 1068 (m), 1030 (m), 990 (m), 745 (m), 702 (s), 606 (m) -1 group P21/c, a ) 12.775(3) Å, b ) 31.326(12) Å, c ) 20.113(3) cm . Magnetic susceptibility: µeff (5-250 K) ) 7.65 µB (500 G, Å, â ) 91.55 (2)°, V ) 8046(4) Å3 determined from 25 reflections C ) 5.87); 7.24 µB (10 kG, C ) 6.56). The compound does not with 13.1° < θ < 16.4°. The 1H NMR spectrum contained only show an absorption maximum from 350 to 800 nm in pyridine. 1H pyridine resonances at 8.54, 7.66, and 7.23 ppm. The compound NMR (THF) revealed only displaced pyridine resonances at 8.61, does not show an absorption maximum from 350 to 800 nm in 7.65, 7.28 ppm. Thermolysis: The compound was treated as in 1. either THF or pyridine. Thermolysis: 100 mg of the sample was X-ray powder diffraction analysis identified TmTe24 as the only placed in a quartz tube under vacuum for 5 min. The tube was crystalline Ln-containing product of the reaction, and GCMS then sealed and the sample temperature was increased at the rate identified Ph2Te as the only organic product. of 20 °C/min with one end of the tube submerged in liquid nitrogen. X-ray Structure Determination of 1, 2, and 4. Data for 1, 2, The temperature was kept between 475 and 490 °Cfor5h.The and 4 were collected on an Enraf-Nonius CAD4 diffractometer with quartz tube was removed and allowed to cool at room temperature. graphite-monochromatized Mo KR radiation (λ ) 0.71073 Å) at Powder diffraction X-ray analysis of the nonvolatile black powder -120 °C. Samples must be completely cooled before exposure to revealed only HoTe.23 Analysis of the residue by GCMS identified any X-ray source. The check reflections measured every hour Ph2Te as the only organic product of the reaction. showed less than 3% intensity variation. The data were corrected Method 2. Holmium metal (0.33 g, 2 mmol) and Hg (0.05 g, for Lorenz effects, polarization, and absorption, the latter by a 0.25 mmol) were added to a solution of diphenyl ditelluride (0.82 numerical (SHELX76)25 method. The structures were solved by g, 2.0 mmol) in pyridine (50 mL). The flask was wrapped in Patterson methods (SHELXS86).26 All non-hydrogen atoms were 2 aluminum foil up to the neck, and after 1 day elemental tellurium refined (SHELXL97) based upon Fobs . All hydrogen atom coor- (0.38 g, 3.0 mmol) was added to the yellow solution that still dinates were calculated with idealized geometries (SHELXL97).27 contained unreacted metal. Two days later all the metal had reacted Scattering factors (fo, f′, f′′) are as described in SHELXL97. and there was a significant amount of dark red precipitate. After Crystallographic data and final R indices for 1, 2, and 4 are heating (60-75 °C, 1 h) to dissolve the precipitate, the solution given in Table 1. Significant bond distances and angles for 1, 2, was filtered to a flask with either a flat bottom (modified and 4 are given in Tables 2, 3, and 4, respectively. Complete Erlenmeyer) or a large round-bottom that was shielded from light. crystallographic details are given in the Supporting Information. The volume was reduced by ca. 3 mL and then saturated by rapid ORTEP diagrams28 for 1, 2, and 4 are shown in Figures 1-3, addition of ca. 8 mL of hexanes. After 2 days, dark red crystals respectively. (0.45 g, 46%) were collected. Results Synthesis of (py)7Tm4(µ4-Te)[(TeTe)4TePh](Te0.6TePh)·2py (4). metal (0.34 g, 2.0 mmol), Hg (0.05 mg, 0.25 mmol), Lanthanide tellurido clusters (py)8Ln4(µ4-Te)(µ2-TeTe)2- and PhTeTePh (0.82 g, 2.0 mmol) were added to pyridine (50 mL), 2 2 (µ2-η ,η -Te5Ph)(Te0.1TePh) [Ln ) Tb(2), Ho(3)] can be the flask was wrapped in aluminum foil, and the mixture was stirred. After 1 day, elemental tellurium (380 mg, 3.0 mmol) was added to (23) The XRPD profile of the Ho thermolysis product matched that for the dark red solution that still contained unreacted Tm. Two days TbTe: Cannon, J.; Hall, H. Inorg. Chem. 1970, 9, 1639 later the metal had reacted and there was a significant amount of (24) (a) Dismuskes, J. P.; White, J. G. Inorg. Chem. 1965, 4, 970. (b) - ° Brixner, L. H. J. Inorg. Nucl. Chem. 1960, 15, 199. (c) Devi, S. U.; dark red precipitate. The flask was heated (60 75 C) for ca. 1 h Singh, S. Solid State Commun. 1984, 52, 303. until all the red precipitate redissolved. The red solution was filtered (25) Sheldrick, G. M. SHELX76, Program for Crystal Structure Determi- and saturated as above to give deep red crystals (0.45 g, 46%) that nation, University of Cambridge, England, 1976. ° (26) Sheldrick, G. M. SHELXS86, Program for the Solution of Crystal did not melt up to 300 C but slowly desolvated and darkened above Structures, University of Go¨ttingen, Germany, 1986. 200 °C. If the crystals are not dried thoroughly before the melting (27) Sheldrick, G. M. SHELXL97, Program for Crystal Structure Refine- point determination, they do not melt but begin turning gray at ca. ment, University of Go¨ttingen, Germany, 1997. 180 °C and become more silver/gray and flaky by 250 °C. Anal. (28) (a) Johnson, C. K.; ORTEP II, Report ORNL-5138. Oak Ridge National Laboratory, Oak Ridge, TN, 1976. (b) Zsolnai, L. XPMA Calcd for C57H55N9Tm4Te11.6: C, 22.6; H, 1.83; N, 4.17. Found: and ZORTEP, Programs for Interactive ORTEP Drawings, University C, 23.2; H, 2.13; N, 3.90. IR: 2923 (s), 1978 (w), 1941 (w), 1864 of Heidelberg, Germany, 1997. 494 Inorganic Chemistry, Vol. 41, No. 3, 2002 Chalcogen-Rich Lanthanide Clusters

Table 2. Significant Distances (Å) and Angles (deg) for 1 Sm(1)-N(1) 2.591(17) Sm(1)-Te(11) 3.067(2) Sm(1)-Te(5) 3.1079(19) Sm(1)-Te(1) 3.1208(18) Sm(1)-Te(2) 3.1261(18) Sm(1)-Te(3 3.1274(18) Sm(1)-Te(4) 3.1599(18) Sm(2)-N(2B) 2.63(2) Sm(2)-N(4) 2.647(17) Sm(2)-N(3) 2.663(17) Sm(2)-N(2A) 2.67(2) Sm(2)-Te(7) 3.1150(18) Sm(2)-Te(6) 3.1498(18) Sm(2)-Te(5) 3.1517(18) Sm(2)-Te(4) 3.2248(18) Sm(2)-Te(1) 3.2316(18) Sm(3)-N(5) 2.620(17) Sm(3)-N(7) 2.662(18) Sm(3)-N(6) 2.673(16) Sm(3)-Te(7) 3.130(2) Sm(3)-Te(9) 3.1436(18) Sm(3)-Te(6) 3.1702(18) Sm(3)-Te(8) 3.1792(19) Sm(3)-Te(1) 3.2740(18) Sm(4)-N(8) 2.571(17) Sm(4)-N(9) 2.583(17) Sm(4)-Te(9) 3.0583(18) Sm(4)-Te(1) 3.0753(18) Sm(4)-Te(3) 3.100(2) Sm(4)-Te(8) 3.0998(18) Sm(4)-Te(2) 3.1678(18) Te(2)-Te(3) 2.771(2) Te(3)-Te(10) 3.849(2) Te(4)-Te(5) 2.764(2) Te(5)-Te(10) 3.617(2) Te(6)-Te(7) 2.909(2) Te(7)-Te(10) 3.156(2) Te(8)-Te(9) 2.940(2) Te(9)-Te(10) 3.085(2) N(1)-Sm(1)-Te(11) 84.9(4) N(1)-Sm(1)-Te(5) 86.0(4) N(5)-Sm(3)-N(7) 132.8(5) N(5)-Sm(3)-N(6) 65.9(5) Te(11)-Sm(1)-Te(5) 128.40(6) N(1)-Sm(1)-Te(1) 169.5(4) N(7)-Sm(3)-N(6) 67.9(5) N(5)-Sm(3)-Te(7) 132.1(4) Te(11)-Sm(1)-Te(1) 105.60(6) Te(5)-Sm(1)-Te(1) 86.91(5) N(7)-Sm(3)-Te(7) 75.7(4) N(6)-Sm(3)-Te(7) 131.7(4) N(1)-Sm(1)-Te(2) 91.4(4) Te(11)-Sm(1)-Te(2) 86.28(5) N(5)-Sm(3)-Te(9) 137.6(4) N(7)-Sm(3)-Te(9) 78.6(4) Te(5)-Sm(1)-Te(2 144.66(5) Te(1)-Sm(1)-Te(2) 89.87(5) N(6)-Sm(3)-Te(9) 124.2(4) Te(7)-Sm(3)-Te(9) 75.73(5) N(1)-Sm(1)-Te(3) 82.5(4) Te(11)-Sm(1)-Te(3) 136.34(5) N(5)-Sm(3)-Te(6) 84.2(4) N(7)-Sm(3)-Te(6) 88.8(4) Te(5)-Sm(1)-Te(3) 92.19(5) Te(1)-Sm(1)-Te(3) 90.04(5) N(6)-Sm(3)-Te(6) 92.8(4) Te(7)-Sm(3)-Te(6) 54.98(4) Te(2)-Sm(1)-Te(3) 52.60(4) N(1)-Sm(1)-Te(4) 89.8(4) Te(9)-Sm(3)-Te(6) 130.71(5) N(5)-Sm(3)-Te(8) 89.8(4) Te(11)-Sm(1)-Te(4) 76.95(5) Te(5)-Sm(1)-Te(4) 52.32(4) N(7)-Sm(3)-Te(8) 94.1(4) N(6)-Sm(3)-Te(8) 83.3(4) Te(1)-Sm(1)-Te(4) 92.05(5) Te(11)-Sm(1)-Te(4) 76.95(5) Te(7)-Sm(3)-Te(8) 131.14(5) Te(9)-Sm(3)-Te(8) 55.42(4) Te(5)-Sm(1)-Te(4) 52.32(4) Te(1)-Sm(1)-Te(4) 92.05(5) Te(6)-Sm(3)-Te(8) 173.75(5) N(5)-Sm(3)-Te(1) 74.7(4) Te(2)-Sm(1)-Te(4) 163.02(5) Te(3)-Sm(1)-Te(4) 144.23(5) N(7)-Sm(3)-Te(1) 151.9(4) N(6)-Sm(3)-Te(1) 140.2(4) N(2B)-Sm(2)-N(4) 66.0(8) N(2B)-Sm(2)-N(3) 131.1(8) Te(7)-Sm(3)-Te(1) 80.14(4) Te(9)-Sm(3)-Te(1) 81.75(4) N(4)-Sm(2)-N(3) 65.2(5) N(2B)-Sm(2)-N(2A) 2.3(12) Te(6)-Sm(3)-Te(1) 89.00(4) Te(8)-Sm(3)-Te(1) 90.97(4) N(4)-Sm(2)-N(2A) 68.1(7) N(3)-Sm(2)-N(2A) 133.3(7) N(8)-Sm(4)-N(9) 89.8(5) N(8)-Sm(4)-Te(9) 95.9(4) N(2B)-Sm(2)-Te(7) 134.1(7) N(4)-Sm(2)-Te(7) 130.4(4) N(9)-Sm(4)-Te(9) 140.4(4) N(8)-Sm(4)-Te(1) 174.5(4) N(3)-Sm(2)-Te(7) 79.7(4) N(2A)-Sm(2)-Te(7) 133.7(7) N(9)-Sm(4)-Te(1) 91.5(4) Te(9)-Sm(4)-Te(1) 86.46(5) N(2B)-Sm(2)-Te(6) 87.3(7) N(4)-Sm(2)-Te(6) 89.5(4) N(8)-Sm(4)-Te(3) 84.0(4) N(9)-Sm(4)-Te(3) 137.2(4) N(3)-Sm(2)-Te(6) 90.1(4) N(2A)-Sm(2)-Te(6) 88.3(7) Te(9)-Sm(4)-Te(3) 82.33(5) Te(1)-Sm(4)-Te(3) 91.41(5) Te(7)-Sm(2)-Te(6) 55.32(4) N(2B)-Sm(2)-Te(5) 134.5(7) N(8)-Sm(4)-Te(8) 89.1(4) N(9)-Sm(4)-Te(8) 84.1(4) N(4)-Sm(2)-Te(5) 124.4(4) N(3)-Sm(2)-Te(5) 78.1(4) Te(9)-Sm(4)-Te(8) 57.03(5) Te(1)-Sm(4)-Te(8) 96.36(5) N(2A)-Sm(2)-Te(5) 132.7(7) Te(7)-Sm(2)-Te(5) 77.04(5) Te(3)-Sm(4)-Te(8) 137.83(5) N(8)-Sm(4)-Te(2) 84.9(4) Te(6)-Sm(2)-Te(5) 132.30(5) N(2B)-Sm(2)-Te(4) 88.7(7) N(9)-Sm(4)-Te(2) 84.9(4) Te(9)-Sm(4)-Te(2) 134.55(5) N(4)-Sm(2)-Te(4) 88.7(4) N(3)-Sm(2)-Te(4) 92.4(4) Te(1)-Sm(4)-Te(2) 89.93(5) Te(3)-Sm(4)-Te(2) 52.46(4) N(2A)-Sm(2)-Te(4) 87.8(7) Te(7)-Sm(2)-Te(4) 128.20(5) Te(8)-Sm(4)-Te(2) 167.42(5) C(1)-Te(10)-Te(9) 94.4(6) Te(6)-Sm(2)-Te(4) 176.06(5) Te(5)-Sm(2)-Te(4) 51.35(4) C(1)-Te(10)-Te(7) 102.5(6) Te(9)-Te(10)-Te(7) 76.20(5) N(2B)-Sm(2)-Te(1) 72.6(7) N(4)-Sm(2)-Te(1) 138.5(4) C(1)-Te(10)-Te(5) 146.7(6) Te(9)-Te(10)-Te(5) 113.99(5) N(3)-Sm(2)-Te(1) 156.3(4) N(2A)-Sm(2)-Te(1) 70.4(6) Te(7)-Te(10)-Te(5) 69.99(4) C(1)-Te(10)-Te(3) 135.0(6) Te(7)-Sm(2)-Te(1) 81.03(5) Te(6)-Sm(2)-Te(1) 90.12(5) Te(9)-Te(10)-Te(3) 70.58(5) Te(7)-Te(10)-Te(3) 113.75(5) Te(5)-Sm(2)-Te(1) 84.29(5) Te(4)-Sm(2)-Te(1) 88.87(5) Te(5)-Te(10)-Te(3) 73.92(4) isolated as pure materials in 35-45% yields from the structure appears general for the middle of the lanthanide reactions of elemental Ln with PhTeTePh and Te in pyridine series, limits are imposed at Sm, which requires manual (reaction 1). isolation, and at Yb, which does not form stable Ln(III) 29 + + f compounds with only Te-based anions. 4Ln 2PhTeTePh 9Te The general structures of 1 and 2 contain a square array (py) Ln (Te)(TeTe) (Te Ph)(Te TePh) (1) - 8 4 2 5 0.1 of Ln(III) ions all connected to a central Te2 . Two edges 2- These compounds cocrystallize with ca. 10% of the tetra- of the square are bridged by (TeTe) , and the Ln coordinat- 2- metallic cluster containing an additional Te atom inserted ing both of these (TeTe) ligands is also coordinated to a into the Ln-TePh bond. The isomorphous Sm cluster terminal TePh. The remaining two edges of the square are also bridged by (TeTe)2-, but the second TePh moiety has (py)9Sm4(Te)(TeTe)2(Te5Ph)(TePh) (1) can also be prepared, but has not yet been isolated (other than by hand) in pure been displaced from a Ln coordination site and instead bonds form. Structural characterization of 1 reveals it to be to two TeTe ligands in a variable fashion, to give what is 5- isomorphous with 2 and 3, but without the compositional formally (TeTeTe(Ph)TeTe). There is a broad range of disorder in the terminal TePh site. A related Tm cluster interactions between TePh and the TeTe units, as illustrated in Figure 4: in 1, there are two clearly asymmetric bonds to (py)7Tm4(µ4-Te)[(TeTe)4TePh](Te0.6TePh) (4) can also be prepared, and again, the product is similarly disordered, with TeTe (differing by 0.07 Å), and the third nearest TeTe unit a TeTePh/TePh occupancy of 62:38. In all compositionally is a further 0.46 Å away. In 2, which has a detectable amount disordered structures, lattice pyridine is also disordered of TeTePh substituting for the terminal TePh, the displaced between two positions, with site occupancies that are directly TePh ligand coordinates the two TeTe units with greater related to the percentage of inserted Te. asymmetry (0.28 Å), and the next nearest TeTe is only 0.34 These compounds are sensitive to oxygen and water, they Å further away from the “Te5Ph” moiety. desolvate when isolated at room temperature, and are (29) Flahaut, J.; Laruelle, P.; Pardo, M.; Guittard, M. Bull Chem. Soc. Fr. sensitive to light throughout the synthetic process. While this 1965, 1399.

Inorganic Chemistry, Vol. 41, No. 3, 2002 495 Freedman et al. Table 3. Significant Distances (Å) and Angles (deg) for 2 Tb(1)-N(2) 2.51(2) Tb(1)-N(1) 2.561(19) Tb(1)-Te(9) 3.021(3) Tb(1)-Te(3) 3.046(3) Tb(1)-Te(1) 3.050(3) Tb(1)-Te(8) 3.077(3) Tb(1)-Te(2) 3.141(3) Tb(2)-N(3) 2.55(2) Tb(2)-Te(11) 2.994(3) Tb(2)-Te(4) 3.073(3) Tb(2)-Te(2) 3.078(3) Tb(2)-Te(3) 3.086(3) Tb(2)-Te(5) 3.127(3) Tb(2)-Te(1) 3.136(3) Tb(3)-N(5) 2.456(19) Tb(3)-N(4) 2.52(2) Tb(3)-Te(7) 3.006(3) Tb(3)-Te(5) 3.020(3) Tb(3)-Te(1) 3.042(3) Tb(3)-Te(6) 3.127(3) Tb(3)-Te(4) 3.151(3) Tb(4)-N(6) 2.560(18) Tb(4)-N(7) 2.57(2) Tb(4)-N(8) 2.63(2) Tb(4)-Te(8) 3.113(3) Tb(4)-Te(7) 3.132(3) Tb(4)-Te(9) 3.137(3) Tb(4)-Te(6) 3.144(3) Tb(4)-Te(1) 3.317(3) Te(2)-Te(3) 2.762(3) Te(3)-Te(10) 3.836(4) Te(4)-Te(5) 2.772(3) Te(5)-Te(10) 3.665(3) Te(6)-Te(7) 2.843(3) Te(7)-Te(10) 3.327(3) Te(8)-Te(9) 2.960(3) Te(9)-Te(10) 3.051(3) N(2)-Tb(1)-N(1) 87.3(7) N(2)-Tb(1)-Te(9) 142.5(5) N(4)-Tb(3)-Te(5) 90.7(5) Te(7)-Tb(3)-Te(5) 81.49(7) N(1)-Tb(1)-Te(9) 98.5(4) N(2)-Tb(1)-Te(3) 135.9(5) N(5)-Tb(3)-Te(1) 90.3(5) N(4)-Tb(3)-Te(1) 169.8(5) N(1)-Tb(1)-Te(3) 86.9(5) Te(9)-Tb(1)-Te(3) 81.47(7) Te(7)-Tb(3)-Te(1) 89.26(7) Te(5)-Tb(3)-Te(1) 91.50(7) N(2)-Tb(1)-Te(1) 88.4(5) N(1)-Tb(1)-Te(1) 174.1(4) N(5)-Tb(3)-Te(6) 86.0(5) N(4)-Tb(3)-Te(6) 91.5(5) Te(9)-Tb(1)-Te(1) 87.35(7) Te(3)-Tb(1)-Te(1) 93.39(7) Te(7)-Tb(3)-Te(6) 55.21(6) Te(5)-Tb(3)-Te(6) 136.22(7) N(2)-Tb(1)-Te(8) 85.4(5) N(1)-Tb(1)-Te(8) 88.4(4) Te(1)-Tb(3)-Te(6) 93.84(8) N(5)-Tb(3)-Te(4) 84.1(5) Te(9)-Tb(1)-Te(8) 58.07(7) Te(3)-Tb(1)-Te(8) 138.02(7) N(4)-Tb(3)-Te(4) 82.7(5) Te(7)-Tb(3)-Te(4) 134.81(7) Te(1)-Tb(1)-Te(8) 95.25(7) N(2)-Tb(1)-Te(2) 83.0(5) Te(5)-Tb(3)-Te(4) 53.33(7) Te(1)-Tb(3)-Te(4) 90.66(7) N(1)-Tb(1)-Te(2) 85.2(4) Te(9)-Tb(1)-Te(2) 134.20(7) Te(6)-Tb(3)-Te(4) 169.17(6) N(6)-Tb(4)-N(7) 67.0(6) Te(3)-Tb(1)-Te(2) 53.01(6) Te(1)-Tb(1)-Te(2) 90.33(7) N(6)-Tb(4)-N(8) 137.0(6) N(7)-Tb(4)-N(8) 70.0(6) Te(8)-Tb(1)-Te(2) 166.93(6) N(3)-Tb(2)-Te(11) 91.3(5) N(6)-Tb(4)-Te(8) 91.2(4) N(7)-Tb(4)-Te(8) 89.3(5) N(3)-Tb(2)-Te(4) 92.3(4) Te(11)-Tb(2)-Te(4) 73.71(8) N(8)-Tb(4)-Te(8) 88.0(5) N(6)-Tb(4)-Te(7) 77.9(4) N(3)-Tb(2)-Te(2) 90.3(4) Te(11)-Tb(2)-Te(2) 89.00(8) N(7)-Tb(4)-Te(7) 126.7(4) N(8)-Tb(4)-Te(7) 131.3(5) Te(4)-Tb(2)-Te(2) 162.55(7) N(3)-Tb(2)-Te(3) 81.3(5) Te(8)-Tb(4)-Te(7) 131.45(7) N(6)-Tb(4)-Te(9) 77.9(4) Te(11)-Tb(2)-Te(3) 141.18(7) Te(4)-Tb(2)-Te(3) 144.18(7) N(7)-Tb(4)-Te(9) 130.3(6) N(8)-Tb(4)-Te(9) 133.7(5) Te(2)-Tb(2)-Te(3) 53.25(6) N(3)-Tb(2)-Te(5) 86.2(5) Te(7)-Tb(4)-Te(9) 74.92(6) N(6)-Tb(4)-Te(6) 93.3(4) Te(11)-Tb(2)-Te(5) 126.54(8) Te(4)-Tb(2)-Te(5 53.10(6) N(7)-Tb(4)-Te(6) 88.6(5) N(8)-Tb(4)-Te(6) 85.9(5) Te(2)-Tb(2)-Te(5) 144.33(7) Te(3)-Tb(2)-Te(5) 91.19(7) Te(8)-Tb(4)-Te(6) 173.82(6) Te(7)-Tb(4)-Te(6) 53.87(6) N(3)-Tb(2)-Te(1) 170.1(5) Te(11)-Tb(2)-Te(1) 98.51(8) Te(9)-Tb(4)-Te(6) 128.67(7) N(6)-Tb(4)-Te(1) 154.2(4) Te(4)-Tb(2)-Te(1) 90.36(7) Te(2)-Tb(2)-Te(1 89.93(7) N(7)-Tb(4)-Te(1) 138.8(5) N(8)-Tb(4)-Te(1) 68.9(4) Te(3)-Tb(2)-Te(1) 90.96(7) Te(5)-Tb(2)-Te(1) 87.80(7) Te(8)-Tb(4)-Te(1) 89.42(7) Te(7)-Tb(4)-Te(1) 82.35(7) N(5)-Tb(3)-N(4) 81.4(7) N(5)-Tb(3)-Te(7) 141.1(5) Te(9)-Tb(4)-Te(1) 80.96(7) Te(6)-Tb(4)-Te(1) 88.37(7) N(4)-Tb(3)-Te(7) 100.9(5) N(5)-Tb(3)-Te(5) 137.4(5) Coordination of TePh to (TeTe)2- effectively decreases The multitude of allowed electronic transitions that are the (TeTe)2- bond length, and the magnitude of the length- entirely ligand based, as well as Te to Ln charge-transfer ening is inversely proportional to the intensity of the excitations, produce a featureless visible spectrum when the PhTe-(TeTe) interaction, as judged by the length of the compounds are redissolved in pyridine. Magnetic susceptibil- PhTe-TeTe bond (Figure 4). For 1, TePh has a bond to ity measurements indicate that there are no interactions Te(9) that is 0.71 Å shorter than the bond to Te(7), and between neighboring Ln(III) ions. Measurements of ø vs T the Te(9)-Te(8) bond is longer, by 0.031(1) Å, than the were obtained for 3 and 4 and are plotted in Figures 5 and Te(7)-Te(6) bond. More dramatically, in 2 the bond from 6, respectively. The ø-1 results reveal distinct Curie Weiss PhTe to Te(9) is 0.276 Å shorter than the bond to Te(7), (CW) behavior [ø ) C /(θ + T)] for both compounds at all and the Te(9)-Te(8) bond is significantly longer, by 0.117- temperatures. (3) Å, than the Te(7)-Te(6) bond. In both 1 and 2, the TeTe Numerous LnTex phases were observed in the thermal ligands that do not interact with TePh have TeTe bond decomposition of 2-4. Both 3 and 4 decompose to give lengths within a well-defined range [2.762(2)-2.772(3) Å] LnTe (reaction 2) of values. (py) Ln (Te)(TeTe) (Te Ph)(TePh) f Cluster 4 is more complex, with significantly weaker x 4 2 5 LnTe + Te + Ph Te + py (2) interactions between the displaced TePh and the two remain- x 2 ing TeTe units, leading to an alternative description of the with elimination of TePh2 and Te. Under identical conditions 9- anionic tellurium fragment as a (Te9Ph) ligand. In 4, the the Tb compound 2 gives TbTe2-x. Phase purity of the final TePh coordinates more strongly to Te(7) and Te(9), and again solid-state product depends significantly on the thermolysis these ditelluride units have TeTe bonds ca. 0.1 Å longer than conditions. If 4 is heated at 550 °C and then cooled slowly, the “uninvolved” TeTe ligands in 1 and 2. In addition, there three products (TmTe, TmTe3, and Tm2Te3) are detected by are additional “bonds” from TePh to Te(5) and Te(3) that XRPD. In contrast, if the sample is first heated and then are only ca. 0.2 Å longer than those to Te(7) and Te(9). In cooled immediately, TmTe is the only crystalline product one of these ligands, there is a clear lengthening of the Te- observed in the XRPD profile. Again, TePh2 was identified (5)-Te(4) bond, to 2.834(11) Å, while in the second ligand as the only volatile product by GCMS. the bond [Te(3)-Te(2), 2.795(11) Å] is less influenced by coordination to the central TePh. Again, in both of these Discussion weaker interactions, the lengthening of the TeTe bond is The comparative ease with which polytellurido compounds inversely proportional to the length of the PhTe-TeTe bond. of the lanthanides can be isolated, relative to the synthesis 496 Inorganic Chemistry, Vol. 41, No. 3, 2002 Chalcogen-Rich Lanthanide Clusters

Table 4. Significant Distances (Å) and Angles (deg) for 4 Tm(1)-N(1) 2.50(2) Tm(1)-Te(2) 2.993(10) Tm(1)-Te(3) 3.000(8) Tm(1)-Te(1A) 3.033(4) Tm(1)-Te(4) 3.060(10) Tm(1)-Te(5) 3.092(9) Tm(1)-Te(1) 3.130(3) Tm(2)-N(3) 2.52(3) Tm(2)-N(2) 2.51(4) Tm(2)-Te(5) 2.993(8) Tm(2)-Te(1) 3.018(8) Tm(2)-Te(7) 3.030(8) Tm(2)-Te(6) 3.056(7) Tm(2)-Te(4) 3.066(7) Tm(3)-N(5) 2.415(18) Tm(3)-N(4) 2.481(17) Tm(3)-Te(9) 2.984(7) Tm(3)-Te(7) 3.005(7) Tm(3)-Te(8) 3.024(8) Tm(3)-Te(1) 3.101(3) Tm(3)-Te(6) 3.101(8) Tm(4)-N(7) 2.37(3) Tm(4)-N(6) 2.43(3) Tm(4)-Te(3) 3.008(8) Tm(4)-Te(9) 3.036(7) Tm(4)-Te(8) 3.044(7) Tm(4)-Te(1) 3.081(8) Tm(4)-Te(2) 3.097(7) Te(2)-Te(3) 2.795(10) Te(3)-Te(10) 3.543(9) Te(4)-Te(5) 2.834(11) Te(5)-Te(10) 3.521(9) Te(6)-Te(7) 2.872(10) Te(7)-Te(10) 3.292(9) Te(8)-Te(9) 2.836(9) Te(9)-Te(10) 3.336(9) N(1)-Tm(1)-Te(2) 93.6(10) N(1)-Tm(1)-Te(3) 90.4(9) N(5)-Tm(3)-N(4) 83.1(8) N(5)-Tm(3)-Te(9) 136.2(9) Te(2)-Tm(1)-Te(3) 55.6(2) N(1)-Tm(1)-Te(1A) 90.8(7) N(4)-Tm(3)-Te(9) 90.0(8) N(5)-Tm(3)-Te(7) 139.2(9) Te(2)-Tm(1)-Te(1A) 85.4(3) Te(3)-Tm(1)-Te(1A) 141.0(3) N(4)-Tm(3)-Te(7) 89.3(7) Te(9)-Tm(3)-Te(7) 83.53(10) N(1)-Tm(1)-Te(4) 86.7(10) Te(2)-Tm(1)-Te(4) 163.98(12) N(5)-Tm(3)-Te(8) 80.5(9) N(4)-Tm(3)-Te(8) 90.8(9) Te(3)-Tm(1)-Te(4) 140.4(2) Te(1A)-Tm(1)-Te(4) 78.5(3) Te(9)-Tm(3)-Te(8) 56.3(2) Te(7)-Tm(3)-Te(8) 139.9(2) N(1)-Tm(1)-Te(5) 85.2(9) Te(2)-Tm(1)-Te(5) 141.2(2) N(5)-Tm(3)-Te(1) 97.6(6) N(4)-Tm(3)-Te(1) 178.8(8) Te(3)-Tm(1)-Te(5) 85.57(12) Te(1A)-Tm(1)-Te(5) 133.3(3) Te(9)-Tm(3)-Te(1) 90.18(16) Te(7)-Tm(3)-Te(1) 89.48(16) Te(4)-Tm(1)-Te(5) 54.9(2) N(1)-Tm(1)-Te(1) 174.3(9) Te(8)-Tm(3)-Te(1) 90.37(19) N(5)-Tm(3)-Te(6) 83.8(9) Te(2)-Tm(1)-Te(1) 90.9(2) Te(3)-Tm(1)-Te(1) 89.31(19) N(4)-Tm(3)-Te(6) 89.7(9) Te(9)-Tm(3)-Te(6) 139.6(2) Te(1A)-Tm(1)-Te(1) 92.99(9) Te(4)-Tm(1)-Te(1) 89.9(2) Te(7)-Tm(3)-Te(6) 56.1(2) Te(8)-Tm(3)-Te(6) 164.06(9) Te(5)-Tm(1)-Te(1) 89.08(18) N(3)-Tm(2)-N(2) 85.5(16) Te(1)-Tm(3)-Te(6) 89.4(2) N(7)-Tm(4)-N(6) 85.9(15) N(3)-Tm(2)-Te(5) 89.7(9) N(2)-Tm(2)-Te(5) 139.5(12) N(7)-Tm(4)-Te(3) 135.8(11) N(6)-Tm(4)-Te(3) 93.2(10) N(3)-Tm(2)-Te(1) 176.4(10) N(2)-Tm(2)-Te(1) 90.8(12) N(7)-Tm(4)-Te(9) 141.7(11) N(6)-Tm(4)-Te(9) 90.7(10) Te(5)-Tm(2)-Te(1) 93.11(19) N(3)-Tm(2)-Te(7) 92.0(10) Te(3)-Tm(4)-Te(9) 82.5(2) N(7)-Tm(4)-Te(8) 86.1(11) N(2)-Tm(2)-Te(7) 138.1(12) Te(5)-Tm(2)-Te(7) 82.1(2) N(6)-Tm(4)-Te(8) 87.1(10) Te(3)-Tm(4)-Te(8) 138.1(2) Te(1)-Tm(2)-Te(7) 90.60(16) N(3)-Tm(2)-Te(6) 87.5(10) Te(9)-Tm(4)-Te(8) 55.60(18) N(7)-Tm(4)-Te(1) 91.8(11) N(2)-Tm(2)-Te(6) 81.8(12) Te(5)-Tm(2)-Te(6) 138.2(3) N(6)-Tm(4)-Te(1) 176.7(10) Te(3)-Tm(4)-Te(1) 90.11(19) Te(1)-Tm(2)-Te(6) 91.81(16) Te(7)-Tm(2)-Te(6) 56.3(2) Te(9)-Tm(4)-Te(1) 89.61(18) Te(8)-Tm(4)-Te(1) 90.40(16) N(3)-Tm(2)-Te(4) 87.8(10) N(2)-Tm(2)-Te(4) 83.9(12) N(7)-Tm(4)-Te(2) 81.3(11) N(6)-Tm(4)-Te(2) 92.1(10) Te(5)-Tm(2)-Te(4) 55.8(2) Te(1)-Tm(2)-Te(4) 91.94(19) Te(3)-Tm(4)-Te(2) 54.5(2) Te(9)-Tm(4)-Te(2) 137.0(3) Te(7)-Tm(2)-Te(4) 137.9(3) Te(6)-Tm(2)-Te(4) 165.2(3) Te(8)-Tm(4)-Te(2) 167.4(3) Te(1)-Tm(4)-Te(2) 89.90(17)

Figure 1. ORTEP diagram of (py)9SmTe(TeTe)2(TeTeTe(Ph)TeTe)(TePh) with the C and H atoms removed for clarity and with the thermal ellipsoids drawn at the 50% probability level. of Ln clusters with Te2-, suggests that the ditellurido ligand Figure 2. ORTEP diagram of (py)8TbTe(TeTe)2(TeTeTe(Ph)TeTe)- 2- stabilizes Ln(III) ions more effectively than Te . These (Te0.1TePh) with the C and H atoms removed for clarity and with the thermal compounds can be prepared either by first adding PhTeTePh ellipsoids drawn at the 50% probability level. to Ln, followed by addition of Te, or in a one-step reaction. - Absence of light throughout the synthetic procedure is crucial Clusters 1 4 share the same fundamental structural to the successful isolation of these cluster compounds, as features recently reported for the sulfur-rich iodo cluster 19 found in the synthesis of tellurolate-capped tellurido clusters (THF)6Yb4(SS)4(S)I2, with a square array of Ln(III) ions, of the transition metals.30 When solutions of the initial the central chalcogenido ligand, and two edges spanned by 2- insertion of Ln into the PhTe-TePh bond were exposed to TeTe units. The central Te resides 1.00 Å (1), 1.11 Å (2), light and the reaction was then insulated, no product was or 1.17 Å (4) above the plane defined by the Ln4 core. When 31 recovered. Similarly, when the first insertion step was corrected for differences in Ln ionic radii, the terminal - insulated but the reaction was then exposed to light, no tellurolate Ln Te bond lengths [1, 3.067(2) Å; 2, 2.994(3) product formed. The compounds are also light-sensitive after Å; 4, 3.033(4) Å] are as expected, given the scant literature - isolation and will turn from red to black within hours under precedent, i.e., the terminal Ln TeR bonds in [(py)2Ho- 32 ambient conditions. (PhNNPh)(TePh)]2 [3.063(1) Å], Cp*2YbTePh(NH3) (3.039-

(30) Corrigan, J.; Fenske, D. Angew. Chem., Int. Ed. Engl. 1997, 36, 1981. (31) Shannon, R. D. Acta Crystallogr., Sect. A 1976, 32, 751.

Inorganic Chemistry, Vol. 41, No. 3, 2002 497 Freedman et al. iodide structural features can be explained by noting that X- is donating electron density into the σ* orbital of the XX, thus lengthening the XX bond. While bond lengths in the TeTe units would to the conclusion that these 5- polytelluride ligands are best described as Te5Ph for 1 and 9- 2 and Te9Ph for 4, there are alternative methods for assessing or qualifying these nebulous interactions. In the literature, there is a general consensus that distances less than 3.75 Å constitute a significant TeTe interaction.39-47 Given this breakpoint, the multitellurium ligands in this work would 5- 7- 9- be described as Te5Ph (1), Te7Ph (2), and Te9Ph (4). A comparison of the poly-Te ligands in 1-4 with the recently described Te(Ph)Te(Ph)Te(Ph) would also be ap- 48 - Figure 3. ORTEP diagram of (py)7TmTe[(TeTe)4TePh](Te0.6TePh) with propriate. Oddly enough, this tritellurolate analogue of I3 the C and H atoms removed for clarity and with the thermal ellipsoids drawn at the 50% probability level. was also obtained in synthetic studies of lanthanide com- pounds, but in this case, introduction of the sterically 6 7 (1) Å), Cp*2Sm(thf)(TeMes) [3.088(2) Å], and La(TeSiR3)3- demanding, highly electronegative ancillary pyrazolylborate 11,12 (DMPE)2 [av 3.155(5) Å]. The Ln-N distances agree ligand completely excludes coordination of Te to the Ln to - with previously reported values for pyridine derivatives of produce an outer sphere (TePh)3 ion. In this unusual anion, - Ln(EPh)3. there are a pair of inequivalent Te Te bonds [3.112(1) Å, The tellurium clusters reported here are also structurally 2.939(1) Å] that are considerably longer than the TeTe bond 49 similar to the recently described selenium-rich clusters in PhTeTePh [2.712(2) Å] and are distinctly similar to the TeTe interactions noted in the present work. (py)8Yb4Se(SeSe)3(SeSeSePh)(SePh) and (py)8Yb4Se(SeSe)3- (SeSeTePh)(SeTePh) that also have an EPh ligand displaced Discrete molecular compounds with ditelluride ligands are 50-53 from a Yb(III) ion and coordinating to an EE moiety.20 The uncommon. Of the reported ditellurides, most are found major difference between the products described here and in combination with chalcophilic metals, and they exhibit a 50 the selenium-rich clusters is the extent that the displaced EPh wide range [i.e., 2.665(2) Å in (R3P)3Ni(TeTe), 2.841(2) 2- 51 - interacts with the EE units. Chemically, the tellurium-rich ÅinMo4Te16 ]ofTe Te bond lengths. There also exists clusters are also considerably more unstable. a limited, but rich, structural chemistry of solid-state materials 52-60 Similarities with polyiodide chemistry are clearly evident with extensive networks of weak TeTe interactions. in the structures. From Figure 4, which shows a schematic Lanthanide complexes are scarce, but again, with highly 5- electronegative, sterically demanding ancillary ligands, com- diagram of the Te5Ph ligands in 1, 2, and 4, it is clear that the interaction of TePh with the TeTe diads depends pounds with ditelluride linkages spanning a pair of Ln(III) ) 5 significantly on environment. In cluster 1, there is a modest ions can be isolated, i.e., [(Cp*)2Ln]2(TeTe) (Ln Sm, asymmetry to the interaction between PhTe and the two TeTe (39) Jobic, S.; Deniard, P.; Brec, R.; Rouxel, J.; Jouanneaux, A.; Fitsch, units. A greater difference is noted in the Tb cluster 2, while A. Z. Anorg. Allg. Chem. 1991, 598/599, 199. (40) Monconduit, L.; Evain, M.; Boucher, F.; Brec, R.; Rouxel, J. Z. Anorg. in 4, the bonding description becomes increasingly less clear. Allg. Chem. 1992, 616, 177. Such a continuum33 of bonding interactions are often found (41) Canadell, E.; Monconduit, L.; Evain, M.; Brec, R.; Rouxel, J.; for the heavier halides, chalcogenides, pnictides, and latter Whangbo, M.-H. Inorg. Chem. 1993, 32, 10. (42) Evain, M.; Monconduit, L.; van der Lee, A.; Brec, R.; Rouxel, J.; transition metals, with chalcogenido interactions being Canadell, E. New J. Chem. 1994, 18, 215. described as complicated van der Waals interactions.33,34 (43) van der Lee, A.; Evain, M.; Monconduit, L.; Brec, R.; Petricek, V. - Inorg. Chem. 1994, 33, 3032. In all three structures, coordination of PhTe to Te(9) (44) Evain, M.; Monconduit, L.; Brec, R. J. Solid State Chem. 1995, 119, Te(8) and Te(7)-Te(6) is clearly more significant, as judged 394. by the shorter PhTe-Te bonds and the considerable (45) Canadell, E.; Jobic, S.; Brec, R.; Rouxel, J.; Whangbo, M.-H. J. Solid 2 State Chem. 1992, 99, 189. lengthening of these Te-Te bonds, relative to the remaining (46) Whangbo, M.-H.; Canadell, E. J. Am. Chem. Soc. 1992, 114, 9587. two ditelluride ligands. Essentially the same features are (47) Canadell, E.; Mathey, Y.; Whangbo, M.-H. J. Am. Chem. Soc. 1988, - 35-38 110, 104. found in the numerous structures of I5 compounds, (48) Hillier, A. C.; Liu, S.; Sella, A.; Elsegood, M. R. J. Angew. Chem., - where I2 units that bond more strongly to the I also Int. Ed. 1999, 38, 2745. - (49) Llabres, P. G.; Dideberg, O.; DuPont, L. Acta Crystallogr. 1972, B28, consistently have the longer I I bond. Both tellurido and 2438. (50) DiVaira, M.; Peruzzini, M.; Stoppioni, A. Angew. Chem., Int. Ed. Engl. (32) Kornienko, A.; Freedman, D.; Emge, T. J.; Brennan, J. G. Inorg. Chem. 1987, 26, 916. 2001, 40, 140. (51) Eichhorn, B. W.; Haltshauer, R. C.; Cotton, F. A.; Wilson, B. Inorg. (33) Pyykko¨, P. Chem. ReV. 1997, 97, 597. Chem. 1988, 27, 4084. (34) Klinkhammer, K. W.; Pyykko, P. Inorg. Chem. 1995, 34, 4134. (52) Sroof, L.; Pennington, W.; Krolis, J. Inorg. Chem. 1992, 31, 2056. (35) Blake, A.; Lippolis, V.; Schroder, M. Chem. Commun. 1996, 2207. (53) Fenske, D.; Steck, J.-C.; Angew. Chem., Int. Ed. Engl. 1993, 32, 238. (36) Ercolani, C.; Pennesi, G.; Trigiante, G. Inorg. Chem. 1995, 34, 2535. (54) Stauf, S.; Reisner, C.; Tremel, W. Chem. Commun. 1996, 1749. (37) Hills, A.; Hughes, D. L.; Leigh, G. J.; Sanders, J. R. J. Chem. Soc., (55) Ibers, J. A.; Bollinger, J. C.; Roof, L. C. Inorg. Chem. 1995, 34, 1430. Dalton Trans. 1991, 61. (56) Smith, D. M.; Roof, L. C.; Ibers, J. A. Inorg. Chem. 1996, 35, 4999. (38) Beno, M.; Geiser, U.; Kostka, K.; Wang, H.; Webb, K.; Firestone, (57) Dhingra, S. S.; Haushalter, R. C. Inorg. Chem. 1994, 33, 2735. M.; Carlson, K.; Nunez, L.; Whangbo, M.; Williams, J. Inorg. Chem. (58) Alemany, P.; Jobic, S.; Brec, R.; Canadell, E. Inorg. Chem. 1997, 36, 1987, 26, 1912. 5050. 498 Inorganic Chemistry, Vol. 41, No. 3, 2002 Chalcogen-Rich Lanthanide Clusters

Figure 4. Bond length variations in the “TeTeTe(Ph)TeTe” ligands in 1 (Sm) and 2 (Tb), the two most significant PhTe-(TeTe) interactions in 4 (Tm), - and variations in typical symmetric and asymmetric I5 ligands. Still, magnetic susceptibility measurements of both com- pounds clearly revealed a complete absence of significant interactions between neighboring Ln(III) spin systems. Plots of 1/ø vs T showed ideal Curie Weiss behavior at all temperatures. Magnetic moments for both 3 (10.6 µB) and 4 (7.60 µB) were found to be surprisingly close to the values 61 for the respective Ln2O3 (Ln ) Ho, µ ) 10.6 µB; Ln ) 62 Tm, µ ) 7.56 µB ), given the extreme sensitivity of the compounds, particularly to light and heat. Of the solid-state telluride compounds available for comparison, only the magnetic properties of Tm2Te3 (µ ) 7.56 µB; Tp )-6K, ideal Curie-Weiss behavior > 10 K)63 have been reported, Figure 5. The temperature-dependent magnetic susceptibility (ø) and its -1 inverse (ø ) for (py)8HoTe(TeTe)2(TeTeTe(Ph)TeTe)(Te0.1TePh). and again, the properties are essentially indistinguishable from those of 4. In the electronic spectra, there are no well-defined absorp- tion maxima for 2-4. Given the multitude of allowed transitions associated with the different Te-Te bonds, the vibrational broadening associated with the PhTe ligand, and the four different Te to Ln CT excitations that tail into the visible spectrum, a featureless spectrum was unfortunately both anticipated and observed. This contrasts with the well- resolved electronic spectrum of (THF)6Yb4(SS)4(S)I2, which has a less complicated chalcogen array, a σ f σ* manifold in the UV spectrum, and only LMCT absorptions shifted Figure 6. The temperature-dependent magnetic susceptibility (ø) and its clearly into the visible spectrum because of the relative -1 inverse (ø ) for (py)7TmTe[(TeTe)4TePh](Te0.6TePh). stability of the Yb(II) excited state.19 Thermolysis. Thermolyses of 2, 3, and 4, give the single- Yb4). In these organometallic compounds, the TeTe bond phase products TbTe - , HoTe, and TmTe, respectively, with lengths are 2.773(1) Å (Sm) and 2.769(1) Å (Yb). There is 2 x 5- 7- 9- elimination of Ph2Te and Te, thus adding to the already no precedence for either (Te5Ph) (Te7Ph), or (Te9Ph). Measuring the magnetic and electronic properties of 3 and (61) Pinaeva, M. M.; Krylov, E. I.; Ryakov, V. M. Inorg. Mater. USSR 4 was complicated by the extreme sensitivity of the samples. 1965, 1, 1428. (62) Perakis, N.; Kern, F. Physik Kond. Mater. 1965, 247, 249. (59) Pell, M. A.; Ibers, J. A. Chem. Mater. 1996, 8, 1386. (63) Pokrzywnicki, S. Sci Papers Inst. Inorg. Chem. Rare Elements (60) Li, J.; Chen. Z.; Emge, T.; Proserpio, D. M. Inorg. Chem. 1997, 36, Wroclaw Polytech Inst. No. 45 1979, 1/69, 45; Chem. Abstr. 1980, 1437. 92, 87141.

Inorganic Chemistry, Vol. 41, No. 3, 2002 499 Freedman et al.

64-68 diverse reactivity patterns noted in Ln(ER)x thermolyses. There are, unfortunately, no well-defined LnTex phase dia- Unusual Te-rich solid-state products might have been grams available in the literature that might help to explain anticipated, given the presence of excess Te in the starting why the individual phases are observed. materials, but the tendency of Te-rich Ln phases to lose Te Conclusion by evaporation is clearly a significant factor in product Tellurido clusters of redox-inactive lanthanides are isolable determination. The elimination of Ph Te has considerable 2 compounds that are oxygen-, water-, heat-, and light-sen- literature precedent.69 Of the comparable lanthanide chalco- sitive. The compounds are clearly trivalent, as judged by genolate thermolyses in the literature, there are certain magnetic susceptibility and X-ray diffraction experiments. similarities with the present work. While most Ln(ER) give 3 These materials are useful single source precursors to solid- Ln E (Ln ) La, Ce; E ) Te; Ln ) Yb, E ) Se; Ln ) Ho, 2 3 state LnTe . Significantly, because tellurolate ligands are so Tm, Yb, E ) S) (reaction 3), LnE (reaction 4) solid-state x readily displaced from Ln coordination spheres, lanthanide phases have been noted with a readily reduced Eu(III) compounds with tellurolate ligands can be useful for doping precursor, and phase-separated (LnSe/LnSe ) products have 2 Ln ions into Te rich matrixes.70 also been observed (reaction 5). Acknowledgment. This work was supported by the f + 2Ln(EPh)3 Ln2E3 3ER2 (3) National Science Foundation under Grant No. CHE-9982625. Supporting Information Available: X-ray crystallographic files f + + 2Ln(EPh)3 2LnE REER 2ER2 (4) in CIF format for the crystal structures of 1, 2, and 4 are available. This material is available free of charge via the Internet at f + + http://pubs.acs.org. 2Ln(EPh)3 LnE2 LnE 3ER2 (5) IC010981W Thermolysis of clusters 2-4 clearly resembles reaction (66) Berardini, M.; Brennan, J. Inorg. Chem. 1995, 34, 6179. 5 with the presence of excess Te accounting for the (67) Lee, J.; Freedman, D.; Melman, J.; Brewer, M.; Sun, L.; Emge, T. J.; observation of the Te-rich phase in 2 and subsequent Te Long, F. H.; Brennan, J. G. Inorg. Chem. 1998, 37, 2512. (68) Lee, J.; Brewer, M.; Berardini, M.; Brennan, J. Inorg. Chem. 1995, evaporation producing the metallic LnTe (NaCl phase) solids. 34, 3215 (69) Brennan, J.; Siegrist, T.; Stuczynski, S.;.Carroll, C.; Rynders, P.; Brus, (64) Brewer, M.; Lee, J.; Brennan, J. G. Inorg. Chem. 1995, 34, 5919. L.; Steigerwald, M. Chem. Mater. 1990, 2, 403. (65) Strzelecki, A. R.; Timinski, P. A.; Helsel, B. A.; Bianconi, P. A. J. (70) Harbison; B. B.; Sanghera; J. S.; Shaw; L. B.; Aggarwal, I. D. US Am. Chem. Soc. 1992, 114, 3159. Patent 6,015,765, 2000.

500 Inorganic Chemistry, Vol. 41, No. 3, 2002